In post-pandemic Europe, migrants will face digital fortress

As the world begins to travel again, Europe is sending migrants a loud message: Stay away! Greek border police are firing bursts of deafening noise from an armored truck over the frontier into Turkey. Mounted on the vehicle, the long-range acoustic device, or "sound cannon," is the size of a small TV set but can match the volume of a jet engine. It's part of a vast array of physical and experimental new digital barriers being installed and tested during the quiet months of the coronavirus pandemic at the 200-kilometer (125-mile) Greek border with Turkey to stop people entering the European Union illegally. Nearby observation towers are being fitted with long-range cameras, night vision, and multiple sensors.